// Formatting library for C++ - std::ostream support
//
// Copyright (c) 2012 - present, Victor Zverovich
// All rights reserved.
//
// For the license information refer to format.h.

#ifndef FMT_OSTREAM_H_
#define FMT_OSTREAM_H_

#include <ostream>

#include "format.h"

FMT_BEGIN_NAMESPACE

template <typename Char>
class basic_printf_parse_context;
template <typename OutputIt, typename Char>
class basic_printf_context;

namespace detail
{

template <class Char>
class formatbuf : public std::basic_streambuf<Char>
{
   private:
    using int_type = typename std::basic_streambuf<Char>::int_type;
    using traits_type = typename std::basic_streambuf<Char>::traits_type;

    buffer<Char> &buffer_;

   public:
    formatbuf(buffer<Char> &buf) : buffer_(buf) {}

   protected:
    // The put-area is actually always empty. This makes the implementation
    // simpler and has the advantage that the streambuf and the buffer are always
    // in sync and sputc never writes into uninitialized memory. The obvious
    // disadvantage is that each call to sputc always results in a (virtual) call
    // to overflow. There is no disadvantage here for sputn since this always
    // results in a call to xsputn.

    int_type overflow(int_type ch = traits_type::eof()) FMT_OVERRIDE
    {
        if (!traits_type::eq_int_type(ch, traits_type::eof()))
            buffer_.push_back(static_cast<Char>(ch));
        return ch;
    }

    std::streamsize xsputn(const Char *s, std::streamsize count) FMT_OVERRIDE
    {
        buffer_.append(s, s + count);
        return count;
    }
};

struct converter
{
    template <typename T, FMT_ENABLE_IF(is_integral<T>::value)>
    converter(T);
};

template <typename Char>
struct test_stream : std::basic_ostream<Char>
{
   private:
    void_t<> operator<<(converter);
};

// Hide insertion operators for built-in types.
template <typename Char, typename Traits>
void_t<> operator<<(std::basic_ostream<Char, Traits> &, Char);
template <typename Char, typename Traits>
void_t<> operator<<(std::basic_ostream<Char, Traits> &, char);
template <typename Traits>
void_t<> operator<<(std::basic_ostream<char, Traits> &, char);
template <typename Traits>
void_t<> operator<<(std::basic_ostream<char, Traits> &, signed char);
template <typename Traits>
void_t<> operator<<(std::basic_ostream<char, Traits> &, unsigned char);

// Checks if T has a user-defined operator<< (e.g. not a member of
// std::ostream).
template <typename T, typename Char>
class is_streamable
{
   private:
    template <typename U>
    static bool_constant<!std::is_same<
        decltype(std::declval<test_stream<Char> &>() << std::declval<U>()), void_t<>>::value>
    test(int);

    template <typename>
    static std::false_type test(...);

    using result = decltype(test<T>(0));

   public:
    is_streamable() = default;

    static const bool value = result::value;
};

// Write the content of buf to os.
template <typename Char>
void write_buffer(std::basic_ostream<Char> &os, buffer<Char> &buf)
{
    const Char *buf_data = buf.data();
    using unsigned_streamsize = std::make_unsigned<std::streamsize>::type;
    unsigned_streamsize size = buf.size();
    unsigned_streamsize max_size = to_unsigned(max_value<std::streamsize>());
    do
    {
        unsigned_streamsize n = size <= max_size ? size : max_size;
        os.write(buf_data, static_cast<std::streamsize>(n));
        buf_data += n;
        size -= n;
    } while (size != 0);
}

template <typename Char, typename T>
void format_value(buffer<Char> &buf, const T &value, locale_ref loc = locale_ref())
{
    formatbuf<Char> format_buf(buf);
    std::basic_ostream<Char> output(&format_buf);
#if !defined(FMT_STATIC_THOUSANDS_SEPARATOR)
    if (loc) output.imbue(loc.get<std::locale>());
#endif
    output << value;
    output.exceptions(std::ios_base::failbit | std::ios_base::badbit);
    buf.try_resize(buf.size());
}

// Formats an object of type T that has an overloaded ostream operator<<.
template <typename T, typename Char>
struct fallback_formatter<T, Char, enable_if_t<is_streamable<T, Char>::value>>
    : private formatter<basic_string_view<Char>, Char>
{
    FMT_CONSTEXPR auto parse(basic_format_parse_context<Char> &ctx) -> decltype(ctx.begin())
    {
        return formatter<basic_string_view<Char>, Char>::parse(ctx);
    }
    template <typename ParseCtx,
              FMT_ENABLE_IF(std::is_same<ParseCtx, basic_printf_parse_context<Char>>::value)>
    auto parse(ParseCtx &ctx) -> decltype(ctx.begin())
    {
        return ctx.begin();
    }

    template <typename OutputIt>
    auto format(const T &value, basic_format_context<OutputIt, Char> &ctx) -> OutputIt
    {
        basic_memory_buffer<Char> buffer;
        format_value(buffer, value, ctx.locale());
        basic_string_view<Char> str(buffer.data(), buffer.size());
        return formatter<basic_string_view<Char>, Char>::format(str, ctx);
    }
    template <typename OutputIt>
    auto format(const T &value, basic_printf_context<OutputIt, Char> &ctx) -> OutputIt
    {
        basic_memory_buffer<Char> buffer;
        format_value(buffer, value, ctx.locale());
        return std::copy(buffer.begin(), buffer.end(), ctx.out());
    }
};
}  // namespace detail

FMT_MODULE_EXPORT
template <typename Char>
void vprint(std::basic_ostream<Char> &os, basic_string_view<Char> format_str,
            basic_format_args<buffer_context<type_identity_t<Char>>> args)
{
    basic_memory_buffer<Char> buffer;
    detail::vformat_to(buffer, format_str, args);
    detail::write_buffer(os, buffer);
}

/**
  \rst
  Prints formatted data to the stream *os*.

  **Example**::

    fmt::print(cerr, "Don't {}!", "panic");
  \endrst
 */
FMT_MODULE_EXPORT
template <typename S, typename... Args,
          typename Char = enable_if_t<detail::is_string<S>::value, char_t<S>>>
void print(std::basic_ostream<Char> &os, const S &format_str, Args &&...args)
{
    vprint(os, to_string_view(format_str), fmt::make_args_checked<Args...>(format_str, args...));
}
FMT_END_NAMESPACE

#endif  // FMT_OSTREAM_H_
